1. Field
Example embodiments of the following disclosure relate to a robot and a control method thereof which control stable walking of the robot in which respective joints are operated by torque servos.
2. Description of the Related Art
In general, walking control technology of a robot which walks with two legs in a similar manner as a human is achieved by controlling joints connecting respective parts of the robot. As control methods of respective joints, there are methods of controlling angles of joints and methods of controlling torques of joints.
In one method of controlling angles of joints, the angles of the respective joints are calculated using inverse kinematics so that a zero moment point (ZMP) is located within a support polygon formed by contact points between feet of a robot and the ground, the respective joints being controlled to maintain the calculated angles. A representative one of the methods of controlling torques of joints is regarded as a passive dynamic walking method, and in this case, the direction of gravity applied to the entirety of a robot is determined as if the robot is placed on an inclined plane, and torques required by the respective joints are generated based on this direction.
In the method of controlling angles of joints, a value of the inverse kinematics is present only if knees of the robot are bent during calculation of the inverse kinematics. However, if the robot walks while bending the knees thereof, a stride is reduced and energy consumption is increased, and thus walking efficiency is lowered.
Further, in the passive dynamic walking method, analysis of walking of the robot in a three-dimensional space is complicated, and thus, two-dimensional walking of the robot is implemented, or even if three-dimensional walking of the robot is implemented, the walking of the robot is not stable and is not natural like walking of a human.